Process for securing chemicals from petroleum residua



1958 c. E. JAHNIG 2,846,360

PROCESS FOR SECURING CHEMICALS FROM PETROLEUM RESIDUA Filed 001;. 20.1954 2 Sheets-Sheet 1 PRODUCTS 4 ISEPARATOR HEAT EXTRACTION 311, l3 ZONECHARGING STOCK CHEhoMCALS c KER T lo T FUEL 4 1 25 AIR Figurel SHOTCOOLING ZONE 25 33 P NET COKE Y PRODUCT CONGVAES ING Charles E. JohnigInventor By C) Attorney ,1 c. E. JAHNIG 2,846,360

PROCESS FOR, SECURING CHEMICALS FROM PETROLEUM RESIDUA Filed Oct. 20,1954 2 SheetsSheet 2 FROM HEATER i TO HEAT 5 EXTRACT|ON CHARGING ZONESTOCK 5H a mo STEAM T0 HEATER Figure 2 Charles E.Jahnig Inventor PROCESSFOR SECURING CHEMIIEALS PETRGLEUM RESHNUA Charles E. Jahnig, Rnnison, N.L, assignor to Esso Rosearch and Engineering Company, a corporation ofDelaware Application October 20, 1954-, derial No. 453,529

10 Claims. (Cl. l9649) This invention relates to the art of convertinghydrocarbons, particularly low value, heavy petroleum residua. It isconcerned with a process for converting oils to products suitable foruse as chemicals or chemical intermediates in a system utilizing heatcarrying particulate solids. In accordance with this invention, heateconomies are effected in a coking process converting comprise petroleumresidua containing refractory con stituents and catalyst contaminantsthat render other methods of upgrading unattractive. Such low value highboiling residual oils are characterized by an API gravity between 10 and20, a Conradson carbon between 5 and 50 wt. percent, and an initialboiling point between 850 and 1200" F. Broadly, however, the presentinvention may find applicability in the converting of charging stockscomprising shale oils, asphalts, tars, pitches, coal tars, syntheticoils, cycle stocks, extracts, recycled heavy ends from the conversionproducts, Whole crudes, heavy distillate or residual fractionstherefrom, and mixtures thereof.

The prior art is familiar with processes wherein petroleum derivativesare converted at high temperatures by contact with heat carryingparticulate solids to obtain low molecular weight hydrocarbon productssuitable for use as chemicals or chemical intermediates upon separationand purification. In prior processes, because of the temperature ofoperation, the heat requirements of the processes have been unduly high.Various schemes have been previously proposed to recapture some of theheat from the conversion products, but they usually involve indirectheat transfer between the conversion products and various other streams.Such indirect heat transfer usually prevents rapid cooling of theproducts and involves fouling of the heat transferring surfaces. Whenconverting petroleum oils at temperatures in the nature of 1400 F.,rapid cooling of the vaporous conversion products within a time of about.01 to 0.10 second is desirable to avoid undue degradation of theconversion products.

In conventional fluidized solids systems for the conversion of oils athigh temperatures, tubular heat exchangers have been used to recoverheat from the high temperature products. The means of heat recovery hasnot proved practical, however, because the dust in the vapors depositson the tubes and greatly reduces heat transfer. The present inventionavoids this problem and accomplishes the desired recovery of heat fromthe conversion products by means of a fluidized solids heat exchangesystem.

It is an object of the present invention to present to the art achemicals coking process that alleviates this problem of heatconservation and other difficulties. Another object is to propose anefficient chemicals coking process utilizing particulate solids as heattransfer media. Still another object of this invention is to devise ahigh temperature petroleum oil conversion process wherein vapor phasecracking of the initial conversion products is at a minimum, and maximumconservation of heat energy obtains.

These and other objects and advantages will become apparent as thisdescription proceeds during which the "attached drawings, forming a partof this specification, are described in detail. These drawings arepresented by Way of illustration only and the present invention is notto be limited thereto.

Figure I illustrates a preferred embodiment of the invention wherein theoil being converted flows concurrently through a transfer line cokeralong with the contact solids and rapid separation of the initialconversion products is obtained by centrifugal force in a simple elbowseparator.

Figure 11 illustrates an alternative design of a chemicals cokingreactor that can be used in the practice of this invention wherein thereis countercurrent flow of the oil and contact solids and wherein theinertia of the relatively coarse contact solids is again utilized tosecure rapid and reasonably complete separation of the conversionproducts from the contact solids.

In brief compass, this invention proposes a hydrocarbon conversionprocess which comprises contacting a charging stock with a stream ofhigh temperature substantially catalytically inert particulate solids ina conversion zone, separating and withdrawing gasiform conversionproducts rapidly from the conversion zone and introducing the conversionproducts into an intermediate portion of a heat extraction zone,downwardly passing relatively cool particulate solids countercurrent tothe conversion products in the heat extraction zone whereby theconversion products are cooled depositing condensate on the relativelycool particulate solids, withdrawing relatively cool convers on productsoverhead from the zone, collecting particulate solids in the lowerportion of the heat extraction zone, cooling and circulating solids fromthe lower portion of the heat extraction zone to the upper portionthereof as the relatively cool particulate solids, and heating andcirculating solids separated from the conversion products in theconversion zone to the inlet thereof as the high temperature particulatesolids.

In a preferred embodiment of the invention, the solids that collect inthe lower portion of the heat extraction zoneare collected in asemi-segregated portion and are Patented Aug. 5, 1958 held resident inthis portion for a time sufiicient to substantially completely convertthe condensate on the solids and to dry the solids, the long timeconversion products being separately withdrawn from the semisegregatedportion.

In another preferred embodiment of the invention, the solids collectedin the bottom portion of the heat extraction zone are stripped and thencooled by contact with a vaporizable liquid medium e. g. water, in acooling zone, the vapors therefrom being used in the process, and thecooled solids therefrom being circulated to the upper portion of theheat extraction zone.

The present invention is also concerned with an improved coking processwherein petroleum hydrocarbons are converted by contact with hightemperature particulate solids, the improvement comprising passing thevaporous conversion products from the chemicals coking zonecountercurrent to a stream of relatively cool particulate solids,whereby the products are cooled and the higher boiling portionstherefrom are condensed on the relaitvely cool solids. The condensatecontaining solids are then subject to long time coking in a segregatedcoking zone to convert the liquid and to dry the solids. The dry solidsare then cooled and recirculated to cool further amounts of theconversion products.

The coking temperatures that can be used in the prac tice of thisinvention may vary from about 120 to 2000 F. Preferably, temperatures inthe range of 1300 to 1600 F. are used. The reheated solids from theheating zone may have an initial temperature 100 to 300 F. above thecoking temperature. Generally stated, a higher initial temperature ofthe reheated solids permits a lower solids to oil circulation ratio tobe used.

The heat carrying particulate solids that are used in the presentinvention may comprise any suitable subdivided material such as metalbeads, sand, metal par ticles, mullite beads, finely divided ceramics,alumina, silicon carbide, etc. Preferably, however, coke produced by theprocess forms the heat carrying solid. Although substantiallycatalytically inert solids are preferably used, this inventionencompasses the use of catalytic solids, either in the coking zone or inthe heat extraction zone, or both. In some applications, particularlywherein lighter oils are being converted, there may be a particularadvantage in using catalytically active solids to obtain a higherconversion and better product distribution, or to permit operations at alower temperature. a

As will appear, the solids are separated from the various gasiformstreams, preferably, by simple change in di rection rather than by theuse of cyclones because cyclones have an undesirably long vapor holdingtime. Therefore, the solids have, preferably, a relatively largeparticle size in the range of about 400 to 5,000 microns, although thesize may range beyond these limits in some cases.

Although the process of this invention may be most advantageouslycarried out in a four-vessel system, c. g., a chemicals coking zone, aheat extraction zone, a solids cooling zone and a heating zone for thecirculated solids, other variations or combinations in the number ofreaction of reaction vessels used will be readily apparent to thoseskilled in the art. Thus, a reduction in the number of vessels can bemade by conducting two or more of the operations in separate orsegregated. zones within one vessel. Y

Any means of circulating solids between zones may be used as desired.Preferably, the solids are circulated using an extraneous gasiformtransporting medium, e. g. steam,;as is known in the art. Reference ismade to copending application Serial No. 439,702 by Whiteley et al, asillustrative of one method of circulating solids applicable to thepresent invention.

The method of reheating the circulating solids forms no part ofthepresent invention. Anyone of several types of heating systems may beused as desired. Thus, fluid bed burners or gravitating bed burnersbesides the transfer line burner illustrated may be used to combust aportion of the circulating coke and to heat the remaining portion, orany other direct or indirect heating means may be used. Shot circulationsystems may be used in certain applications. Further, extraneous liquidor gaseous fuels may be burned in preference to the coke particles tosupply heat thereto.

The operating conditions relating to the following example areconveniently summarized in Table I. Referring now to the attached FigureI, the major items of equipment shown are a chemicals coking zone 1, aheat extraction zone 2, with a long time coking zone 2a in the bottomportion thereof, a solids cooling zone 3, and a product separation zone4. High temperature solids are admitted to the inlet of the coking zoneby line 5 and contact the charging stock supplied by line 7. Steam, orother conveying gas, is admitted to the coking zone by line 10 andconveys the solids and gases therethrough at velocities above about 10feet per second, e. g., 40 feed per second.

The charging stock may, of course, be suitably preheated as by heatexchange with the various product streams, and may also be admixed witha dispersing medium, e. g. steam, to obtain better contact between thesolids and the liquid. The injected charging stock, upon contact withthe high temperature solids, undergoes pyrolysis evolving hydrocarbonvapors and depositing carbonaceous residue on the solids. Initialconversion of a charging stock in this zone preferably ranges from 20 toconversion to propane and lighter products. An elbow separator is'usedto separate the contact solids from the conversion products. In passingaround the bend, the solids are forced to the outside and the conversionproducts are withdrawn radially from the interior of the bend by line11. The solids, after the separation, pass downwardly into an expandedsettling zone 6. Because of the high temperature of the solids, theparticles are substantially completely dried. Some stripping steam maybe admitted to the base of the settling zone to sweep out hydrocarbons,the vapors being removed as product by line 9.

The conversion products enter heat extraction zone 2 from line 11wherein they contact cool free falling solids and are thereby rapidlycooled below cracking temperatures, e. g., below 800 to 1000 F. Bailles12 or similar mixing means may be conveniently used in this sector topromote the efficiency of contacting. The heavier portions of the vaporsare condensed on the solids, and the condensate and the solids collectin the lower portion 2a of the zone. The now cooled conversion productsat vapor temperatures in the range of 500 to 800 F. are removed from theheat extraction via line 13. The conversion products may be separated asdesired to obtain the various products fractions desired.' As shown,they are initially scrubbed in separator zone 4 with a reflux oil toremove the higher boiling portions of the vapors. This higher boilingportion may have initial boiling point in the range of 500 to 800 F. Aportion of the oil so condensed may be passed by line 14 to line 11 topartially quench the temperature conversion products, as is hereinafterdescribed. Another portion may be recycled and cooled via line to serveas a reflux or scrubbing oil. Desirably, the remainder is recycled vialine 16 to the coking zone to be treated substantially to extinctiontherein although some of this condensed material, which will be highlyaromatic, can be removed from the process as product by line 17.

Returning to the heat extraction zone, the wet solids collected in thelower zone 2a may be stripped and then transferred to cooling zone 3.However, this permits mingling of the long time'conversion productswiththe primary conversion products which may be disadvantageous in certainapplications. Preferably, the lower portion of the heat extraction zoneis separated from the upper portion by bathe 18 or other means, and thecoke and the condensate collected thereon are held resident in the lowerzone at a temperature of about 1000 to 1400 F. to substantiallycompletely convert the condensed material. 'Ihe long time gasiformconversion products formed therein are removed by line 19 and may beseparated by conventional means. Both the products in line 19 and theproducts removed from separator 4 via line 20 can be separated as byfractionation, absorption, crystalization extraction etc. to obtainproducts of the desired purity and boiling range.

The solids in the bottom of the heat extractionare withdrawn andtransferred to cooling zone 3 via line 21 or other means. A portion ofthese solids may be trans ferred by line 22 to the heating zone, asdescribed hereinafter. Water is injected into the cooling zone by line23 and contacts the high temperature solids therein. Preferably, thesolids are maintained as a fluidized bed, or they can be in the form ofa moving fixed bed. In some cases steam only may be injected into thezone to be super-heated as by line 23a, or steam-water mixtures may beinjected. The steam generated in the cooling zoneis removed from theupper portion of the zone by line 24 and may be utilized to fluidize thesolids in the lower portions of zone 6 and heat extraction zone 2.Because it is desirable to use a diluent when coking to producechemically, a major portion of the steam is preferably transferred tovessel 1 by line 10. Dependent upon the circulation rate a sufiicientamount of water is introduced in the zone to cool the solids toa'temperature in the range of about 300 to 700 F. Additional heat may beremoved via exchanger 35, and used to preheat feed, etc. The cool solidsare circulated from the zone by line 25 to the upper portion of the heatextraction zone. A conveying gas, e. g. steam, is admitted to line 25 byline 26 to aid in the transportation of the solids as is known by theart. The net coke product of the process can conveniently be removedfrom the cooling zone by line 33.

To supply heat to the process, solids are transferred from the bottom ofthe coking zone by line 27 to a heating zone, e. g., transfer lineburner 28. Air is admitted to the base of the burner by line 29 andserves'not only to partially combust the particles but also to conveyvia entrainment the particles through the elongated burner at velocitiesabove about feet per second, e. g., 40 feet per second. As previouslymentioned, extraneous fuels can be admitted to the heating zone by line30. After passing through the burner the heated solids are removed fromthe flue gases in cyclone 31, the flue gases being withdrawn via line32. The heated solids are then transferred by line 5 to the coking zone.

In some applications, particularly when relatively high temperatures arebeing used, it may be desired to at least partially quench the initialconversion products in line 11. Steam, water, cool solids etc. may beused to accomplish this quenching. It is preferred, however, to use aheavy oil fraction to attain this quenching. Thus, line 14 can injectsuthcient amount of the heavier ends separated from the vapors inseparator 4 to cool the initial conversion products. Preferably, theproducts are only cooled in this "alternative mode of operation only byabout 200 F. to avoid undue heat loss.

From this description it will be apparent that two different types ofsolids, e. g., catalytic and non-catalytic, of perhaps diiferentparticles size may be circulated in the chemicals coker-heating zonecircuit and in the heat extraction zone-cooling zone circuit.

The following Table 1 summarizes the pertinent range of operatingconditions applicable to the present invention illustrated in Figure Iand presents a specific example of operating conditions. Table IIillustrates the products obtainable from the charging stock indicatedwhen the process is operated in accordance with the example of Table I.

Table I Range Example Pressures, p. s. i.:

In chemicals coker vapor outlet 0-400 7 In heat extraction zone vaporoutlet 0-400 5 In shot cooler vapor outlet 0-400 15 Inlet of transferline burner 1-10 3 Temperatures, F.:

Outlet of transfer line burner 1, 400-2, 000 1, 500 Solids settling zoneof chemicals coker 1, 200-1, 800 1,300 Vapors passed to heat extractionzone"--. 1, 200-1, 800 1, 325 Bottom of heat extraction zone. 1, 000-1,700 1, 125 Vapors from heat extraction zone 400-900 600 Shot cooler atbottom 250-500 400 Coke Circulation, lbs/lb. fresh feed:

Heated solids to chemicals coker. 5-20 15 0001 solids to heat exchangezone 0. 5-10 2 Solids from heat exchange zone to cooling zone 0. 5-10 2Solids from heat exchange zone to heating zone 0-5 1 Net product coke 0.05-. -10 20 Conversion, 1 basis 03-:

In chemicals coking zone.-. 20-60 30 Overall conversion -80 35 Steam,wt. percent of fresh feed:

To chemicals coker 5-50 10 To heat exchange zone p 1-5 3 Recycle stock,wt. percent of fresh feed 5-50 20 Initial boiling point, F 400-800 650 1Oaconversion is defined as: wt. percent feed less wt. percent ofprrodhufctsd having 3 carbon atoms and less, excluding coke, based en esee Table II Charging stock: 2.4% South Louisiana residuum Inspections:

10.7, API gravity 17, Oonradson carbon 1100 F initial boiling point0.74, wt. percent sulphur 0.48, wt. percent ash 1100 F.

396, SSF viscosity 210 F.

F., pour Products: Wt. percent of fresh feed:

1 Excluding benzene.

Referring now to Figure II, there is shown an alternative apparatus forcarrying out the chemicals coking reaction. Parts similar to those inFigure l have the same numerical designation, being diiferentiated bythe prefix 5. The charging stock is injected into the coking zone vialines 57 and 57a wherein. it contacts high temperature fluidized solidsin the lower portion of the zone and undergoes pyrolysis. Steam suppliedby line 510 may be used to disperse the oil. The reheated solids areadmitted to the upper portion of the zone by line 55 and maybe suitablydispersed throughout the zone by distributing bars or grid 61. Thevapors generated in the lower portion rise countercurrently to thefalling solids and are further cracked. The conversion products are thenrapidly removed from the contact solids by being transversely withdrawnfrom the coking zone via line 511 and are passed to the heat extractionzone. The contact solids used in this arrangement are, preferably,relatively coarse so as to favor this separation.

The contact solids are collected as a fluidized bed in the lower portionand are stripped with steam supplied by line 510a before beingcirculated to a heating zone to be reheated.

Having described the invention, other variations will become apparent tothose skilled in the art. For example, the system of Figure II isadaptable to processing mixed feed streams. Thus, a more refractorymaterial such as a cycle stock may be introduced into the lower portionof the reactor of Figure II as shown wherein it can have a longercontact'time, and a lighter stock such as a gas oil may be introducedinto the upper portion via line 57b. Furthen the reheated solids neednot only be introduced into the coking zones as illustrated,'but aportion of the reheated solids maybe separately introduced into thesettling zone of the coking zone of Figure I and into thelower'pprtionjof the coking zone of Figure II containing the fluid bedwhereby independent temperature controlcanbe maintained in theseportions.

Having described the invention what is sought to be protected by LettersPatent js'succinctly set forth in the following claims.

What is claimed is:

1. A hydrocarbon conversion process for the production of chemicalswhich comprises contacting a heavy hydrocarbon oil charging stock with astream of high temperature substantially catalytically inert particulatesolids in a conversion zone at a temperature in the range of 1200" to2000 F rapidly separating and'withdrawing gasiform conversion productsand introducing the conversion products into an intermediate portion ofan extraneous heat extraction Zone, downwardly passing relatively cool,substantially non-entrainable, particulate solids countercurrent to saidconversion products in said heat extraction zone whereby said conversionproducts are cooled depositing condensate on said relatively coolparticulate solids, withdrawing relatively cool conversion productsoverhead from said zone, collecting particulate solids in a lowersegregated portion of said heat extraction zone, long term conversionproducts being separately withdrawn from said segregated portion, thesolids remaining resident in said segregated portion at a temperature inthe range of 1000 to 1700 F., and for a time sufficient to substantiallycompletely convert the condensate thereon and to dry said solids,cooling and stripping solids from the lower portion of said heatextraction zone in an enlarged settling zone and recirculating them tothe upper portion of the heat extraction zone as said relatively coolparticulate solids, and reheatingand returning solids separated fromsaidconversion products to said conversion zone.

2. The process of claim 1 wherein said conversion zone comprises atransfer line zone and wherein the gasiform conversion products areseparated by centrifugal force in an elbow separator, the gases beingwithdrawn radially from the inner part of said separator.

3. The process of claim 1 wherein said charging stock comprisespetroleum hydrocarbons having an API gravity in the range of -10 to 20,a Conradson carbon in the range of 5 to 50 wt. percent, and an initialboiling point in the range of 850 to 1200 F. I

4. The process of claim 1 wherein said conversion zone is verticallydisposed, wherein said particulate solids fall downwardly therethrough,and wherein said conversion products are separated by being withdrawnfrom an intermediate portion of said conversion zone transversely to theflow path of the solids.

5. The process of claim 1 wherein said particulate solids comprisepetroleum coke produced by the process having a particle sizesubstantially in the range of 400 to 2000 microns.

6. The process of claim 1 wherein said particulate solids circulatedfrom the lower portion of said heat eX- traction zone to the upperportion thereof are cooled by contact with a vaporizable liquid mediumin the settling cooling zone, the vapors therefrom being used in theprocess.

7. The process of claim 6 wherein said vaporizable liquid mediumcomprises water, and the steam generated thereby is utilized asstripping and diluting media in said conversion and heat extractionzones.

8. The process of claim 1 wherein the higher boiling portion of saidrelatively cool conversion products is separated therefrom, and isutilized to partially quench the gasiform conversion products withdrawnfrom said conversion zone.

9. A process for the production of petro-chemicals and intermediatescomprising the steps of heating particulate solids to a temperature inthe range of l400 to 2000" R, passing the solids so heated through aconversion zone, contacting a charging stock with the heated solids inproportions of 5 to 20 lbs. of solids per pound of said charging stockthereby forming gasiform conversion products and carbonaceous residuewhich is deposited on the solids, withdrawing said gasiform conversionproducts from said conversion zone transversely to the path of flow ofthe solids, passing the conversion products countercurrently to a streamof relatively cool particulate solids in proportions of 0.5 to 10 lbs.of solids per pound of said charging stock whereby said conversionproducts are cooled to a temperature below 900 F. depositing condensateon said solids, withdrawing said conversion products so cooled overheadfrom said heat extraction zone, collecting solids in a separate lowerportion of said heat extraction zone and permitting the solids to remainresident therein for a time and at a temperature in the range of 1000 to1700 F. sufficient to convert said condensate, separately withdrawingfrom said lower portion the long time conversion products, stripping andpassing solids from the lower portion of said heat eX- traction zone toa cooling zone, introducing water into the' cooling zone to cool thesolids therein'to a temperature below 500 F. and to generate steam,utilizing the steam so generated in the process, passing cool solidsfrom said cooling zone to the upper portion of said heat extractionzone, and transferring stripped solids from said conversion zone througha heating zone to the inlet portion of said conversion zone, the initialC conversion of charging stockin said conversion zone being in the rangeof 20 to wt. percent, and the ultimate'C conversion of said chargingstock being in the range of 25 to 10. The process of claim 9 wherein theaverage residence time of said gasiform conversion products before beingcooled is less than 0.1 second.

1. A HYDROCARBON CONVERSION PROCESS FOR THE PRODUCTION OF CHEMICALSWHICH COMPRISES CONTACTING A HEAVY HYDROCARBON OIL CHARGING STOCK WITH ASTREAM OF HIGH TEMPERATURE SUBSTANTIALLY CATALYTICALLY INERT PARTICULATESOLIDS IN A CONVERSION ZONE AT A TEMPERATURE IN THE RANE OF 1200* TO2000*F., RAPIDLY SEPARATING AND WITHDRAWING GASIFORM CONVERSION PRODUCTSAND INTRODUCING THE CONVERSION PRODUCTS INTO AN INTERMEDIATE PORTION OFAN EXTRANEOUS HEAT EXTRACTION ZONE, DOWNWARDLY PASSING RELATIVELY COOL,SUBSTANTIALLY NON-ENTRAINABLE, PARTICULATE SOLIDS COUNTERCURRENT TO SAIDCONVERSION PRODUCTS IN SAID HEAT EXTRACTION ZONE WHEREBY SAID CONVERSIONPRODUCTS ARE COOLED DEPOSITING CONDENSATE ON SAID RELATIVELY COOLPARTICULATE SOLIDS, WITHDRAWING RELATIVELY COOL CONVERSION PRODUCTSOVERHEAD FROM SAID ZONE, COLLECTING PARTICULATE SOLIDS IN A LOWERSEGREGATED PORTION OF SAID HEAT EXTRACTION ZONE, LONG TERM CONVERSIONPRODUCTS BEING SEPATATELY WITHDRAWN FROM SAID SEGREGATED PORTION, THESOLIDS REMAINING RESIDENT IN SAID SEGREGATED PORTION AT A TEMPERATURE INTHE RANGE OF 1000* TO 1700*F., AND FOR A TIME SUFFICIENT TOSUBSTANTIALLY COMPLETELY CONVERT THE CONDENSATE THEREON AND TO DRY SAIDSOLID, COOLING AND STRIPPING SOLIDS FROM THE LOWER PORTION OF SAID HEATEXTRACTION ZONE IN AN ENLARGED SETTLING ZONE AND RECIRCULATING THEM TOTHE UPPER PORTION OF THE HEAT EXTRACTION ZONE AS SAID RELATIVELY COOLPARTICULATE SOLIDS, AND REHEATING AND RETURNING SOLIDS SEPARATED FROMSAID CONVERSION PRODUCTS TO SAID CONVERSION ZONE.